If you are using the Command Line build step (and not the TeamCity-provided Docker steps), these parameters can be used as agent requirements to ensure your build is run only on the agents with Docker installed.

Features

TeamСity-Docker integration provides the following features which facilitate working with Docker under TeamCity:

Docker Support Build Feature

Adding this build feature will enable Docker events monitoring: such operations as docker pull and docker run will be detected.The build feature adds the Docker Info tab to the build results page providing information on Docker-related operations. It also provides the following options:

ability to clean-up the images

automatic login to an authenticated registry before the build and logout of it after the build

These options require a configured connection to a docker registry:

Clean-up of images

If you have a build configuration which publishes images, you need to remove them at some point. You can select the corresponding option and instruct TeamCity to remove the images published by a certain build when the build itself is cleaned up. It works as follows: when an image is published, TeamCity stores the information about the registry of the images published by the build. When the server clean-up is run and it deletes the build, all the configured connections are searched for the address of this registry, and the images published by the build are cleaned up using the credentials specified in the connection found.

Automatic Login to/Logout of Docker Registry

If you need to log in to a registry requiring authentication before a build, select the corresponding option and a connection to Docker configured in the project settings.Automatic logout will be performed after the build finishes.

Docker Connection for a Project

The Project Settings | Connections page allows you to configure a connection to docker.io (default) or a private Docker registry. More than one connection can be added to the project. The connection will be available in all the subprojects and build configurations of the current project.

Connecting to Insecure Registry

To connect to an insecure registry:

Configure all TeamCity agents where Docker is installed to work with insecure repositories as stated in the Docker documentation. This is sufficient to allow the connection to the private registry over HTTP.

To connect to an insecure registry over HTTPS with a self-signed certificate, in addition to the step above, import the self-signed certificate to the JVM of the TeamCity server as described here. You can consult the Docker documentation on using self-signed certificates.

Docker Runner

The Docker runner supports the build, push, and tag Docker commands.

When creating TeamCity projects / build configurations from a repository URL, the runner is offered as build step during auto-detection, provided a Dockerfile is present in the VCS repository.

Docker Command

Here is the list of the Docker commands. Depending on the selected command, the settings below will vary.

Command

Parameter

Description

build

Dockerfile source

Depending on the selected source, the settings below will vary. The available options include File, a URL or File content.

Path to file

Available if File is selected as the source. Specify the path to the Docker file. The path should be relative to the checkout directory.

Context folder

Available if File is selected as the source. Specify the context for the Docker build. If blank, the enclosing folder for Dockerfile will be used.

URL to file

Available if URL is selected as the source. The URL can refer to three kinds of resources: Git repositories, pre-packaged tarball contexts, and plain text files. See the Docker documentation for details.

File Content

Available if the file cis selected as the source. You can enter the content of the Dockerfile into the field.

Running Docker via sudo

Since TeamCity 2019.1.2, you can enforce starting Docker commands on a TeamCity agent via sudo. Add the teamcity.docker.use.sudo=true setting in the build agent configuration file or as an agent's system property. On an agent start, the TeamCity agent log will inform that the sudo prefix is used to run Docker commands.

To configure the sudoers file for the sudo command, use visudo as follows:

buildagentuser ALL=(ALL) NOPASSWD:SETENV:<full_path_to_docker>

We recommend removing (or commenting out) the Defaults requiretty line from the sudoers file to prevent the problem with docker login.

Docker Compose Runner

The runner allows starting Docker Compose build services and shutting down those services at the end of the build.

The Docker Compose runner supports one or several Docker Compose YAML file(s) with a description of the services to be used during the build. The path to the docker-compose.yml file(s) should be relative to the checkout directory. When specifying several files, separate them with a space.

The executed commands are:

# The commands are executed with the current working directory, where the docker-compose file resides.
docker-compose -f <docker-compose.yml> [-f <docker-compose2.yml>] up -d
# At the end of the build, for each docker compose build step the build agent will run:
docker-compose -f <docker-compose.yml> [-f <docker-compose2.yml>] down -v

If the checkbox pull image explicitly is enabled, docker-compose pull will be run before the docker-compose up command.

When using Docker Compose with images which support HEALTHCHECK, TeamCity will wait for the healthy status of all containers that support this parameter.

If the start of Docker Compose was successful, the TeamCity agent will register the TEAMCITY_DOCKER_NETWORK environment variable containing the name of the Docker Compose default network. This network will be passed transparently to the Docker Wrapper when used in some build runners.

Docker Wrapper

TeamCity provides the Docker Wrapper extension for Command Line, Maven, Ant, and Gradle runners. Each of the supported runners has the dedicated Docker settings section.

Docker Settings

In this section, you can specify a Docker image which will be used to run the build step. Once an image is specified, all the following options are available:

Setting

Description

Run step within Docker container

Specify a Docker image here. TeamCity will start a container from the specified image and will try to run this build step within this container.

Docker image platform

Select <Any> (default), Linux or Windows.

Pull image explicitly

If the checkbox is enabled, docker pull <imageName> will be run before the docker run command.

Additional docker run arguments

The Edit arguments field allows specifying additional options for docker run. The default argument is --rm, but you can provide more, for instance, to add an additional volume mapping.

In this field, you cannot reference environment variables using `%env.FOO_BAR%` syntax because TeamCity does not pass environment variables from build agent into docker container. If you need to reference an environment variable on agent, define configuration parameter `system.FOO_BAR=env_var_value` in buildAgent.properties and reference it via `%system.FOO_BAR%`

How It Works

Technically, the command of the build runner is wrapped in a shell script, and this script is executed inside a Docker container with the docker run command. All the details about the started process, text of the script, and so on, are written into the build log (the Verbose mode enables viewing them).

The checkout directory and most build agent directories are mapped inside the Docker process.

At the end of the build step with the Docker wrapper, a build agent runs the chown command to restore access of the buildAgent user to the checkout directory. This mitigates a possible problem when the files from a Docker container are created with the root ownership and cannot be removed by the build agent later.

If the process environment contains the TEAMCITY_DOCKER_NETWORK environment variable set by the previous Docker Compose build step, this network is passed to the started docker run command with the --network switch.

Environment Variables Handling

TeamCity passes environment variables from the build configuration into the Docker process, but it does not pass environment variables from the build agent, as they may not be relevant to the Docker container environment. The list of the passed environment variables can be seen in Verbose mode in the build log.

Docker Disk Space Cleaner

Docker Disk Space Cleaner is an extension to the Free Disk Space build feature ensuring a certain amount of disk space for a build.